Water heater



FIG. 1 is a perspective view of a water heater showing our new design;

FIG. 2 is a front view thereof;

FIG. 3 is a rear view thereof;

FIG. 4 is a top plan view thereof;

FIG. 5 is a bottom plan view thereof;

FIG. 6 is a right side view thereof; and,

FIG. 7 is a left side view thereof.

The broken lines illustrate portions of the water heater that form no part of the claimed design. 

CLAIM The ornamental design for a water heater, as shown and described. 